Quoted from cjchand:
Having an intermittent issue with my HS where it has blown fuse F4 a couple of times. I looked on the CPU board and saw that Q73 has a leg scorched (see attached pic). It tests OK with a DMM, but I get that how it tests without power doesn’t mean it’s good when powered on.
Just an update for posterity. Took nearly 300 games for the issue to come back, but think I might have the root cause. After this recent failure, I popped a fuse back in and played, videoing as I played.
In this case, it went when I hit the right flipper, which made no sense. The fuse blowing is for the special solenoids. But, it did hit the left sling just before I flipped. I found that the left sling was mechanically bound up. It would only go halfway through it’s stroke. I took everything apart, but didn’t find anything obvious.
I guess it would make sense that if it never hit its EOS, that would pop the fuse.
So, don’t know exactly why the sling bound up, but will order new hardware for both. Luckily, the left coil seems to be in good shape (no scorching, sleeve came right out).
Also, seems that the burning on the tranny for Q73 might be a red herring. Plan on replacing it, and the other bits in the chain soon.
Will update if anything new transpires.